When two private military contractors are murdered, the team's investigation leads them back to one of their unsolved cases from the episode, Impact with the search bringing OSP to a suspect who eventually puts one of their own in grave danger while Sam sets up Callen on a blind date. Sam and Callen search in Mexico for a diplomatic murder suspect. Nate and Deeks assist the pair from Los Angeles. InLos Angeles, Sam and Callen investigate the explosion of a fish market with the help of an undercover DEA agent, Talia Del Campo (Mercedes Masohn). In Afghanistan, Kensi and Granger are on the case of a helicopter crash.